    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *     http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.configuration2.builder.combined;
    018
    019import java.util.Arrays;
    020import java.util.Collection;
    021
    022import org.apache.commons.configuration2.CombinedConfiguration;
    023import org.apache.commons.configuration2.Configuration;
    024import org.apache.commons.configuration2.builder.BasicBuilderParameters;
    025import org.apache.commons.configuration2.builder.BasicConfigurationBuilder;
    026import org.apache.commons.configuration2.builder.BuilderParameters;
    027
    028/**
    029 * <p>
    030 * A specialized {@code ConfigurationBuilderProvider} implementation which deals
    031 * with combined configuration builders.
    032 * </p>
    033 * <p>
    034 * This class is used to support {@code <configuration>} elements in
    035 * configuration definition files. The provider creates another
    036 * {@link CombinedConfigurationBuilder} which inherits some of the properties
    037 * from its parent builder.
    038 * </p>
    039 *
    040 * @version $Id: CombinedConfigurationBuilderProvider.java 1842194 2018-09-27 22:24:23Z ggregory $
    041 * @since 2.0
    042 */
    043public class CombinedConfigurationBuilderProvider extends
    044        BaseConfigurationBuilderProvider
    045{
    046    /** Constant for the name of the supported builder class. */
    047    private static final String BUILDER_CLASS =
    048            "org.apache.commons.configuration2.builder.combined.CombinedConfigurationBuilder";
    049
    050    /** Constant for the name of the supported reloading builder class. */
    051    private static final String RELOADING_BUILDER_CLASS =
    052            "org.apache.commons.configuration2.builder.combined.ReloadingCombinedConfigurationBuilder";
    053
    054    /** Constant for the name of the supported configuration class. */
    055    private static final String CONFIGURATION_CLASS =
    056            "org.apache.commons.configuration2.CombinedConfiguration";
    057
    058    /** Constant for the combined configuration builder parameters class. */
    059    private static final String COMBINED_PARAMS =
    060            "org.apache.commons.configuration2.builder.combined.CombinedBuilderParametersImpl";
    061
    062    /** Constant for the name of the file-based builder parameters class. */
    063    private static final String FILE_PARAMS =
    064            "org.apache.commons.configuration2.builder.FileBasedBuilderParametersImpl";
    065
    066    /**
    067     * Creates a new instance of {@code CombinedConfigurationBuilderProvider}.
    068     */
    069    public CombinedConfigurationBuilderProvider()
    070    {
    071        super(BUILDER_CLASS, RELOADING_BUILDER_CLASS, CONFIGURATION_CLASS,
    072                Arrays.asList(COMBINED_PARAMS, FILE_PARAMS));
    073    }
    074
    075    /**
    076     * {@inheritDoc} This implementation creates the result builder object
    077     * directly, not using reflection. (The reflection-based approach of the
    078     * base class does not work here because a combined configuration builder
    079     * has constructors with a different signature.) It also performs some
    080     * additional initializations.
    081     */
    082    @Override
    083    protected BasicConfigurationBuilder<? extends Configuration> createBuilder(
    084            final ConfigurationDeclaration decl, final Collection<BuilderParameters> params)
    085            throws Exception
    086    {
    087        CombinedConfigurationBuilder builder;
    088        if (decl.isReload())
    089        {
    090            builder = new ReloadingCombinedConfigurationBuilder();
    091        }
    092        else
    093        {
    094            builder = new CombinedConfigurationBuilder();
    095        }
    096        decl.getConfigurationBuilder().initChildEventListeners(builder);
    097        return builder;
    098    }
    099
    100    /**
    101     * {@inheritDoc} This implementation pre-fills basic parameters from the
    102     * basic properties of the parent builder's result configuration.
    103     */
    104    @Override
    105    protected void initializeParameterObjects(final ConfigurationDeclaration decl,
    106            final Collection<BuilderParameters> params) throws Exception
    107    {
    108        // we know that the first object is the combined builder parameters
    109        // object
    110        final BasicBuilderParameters basicParams =
    111                (BasicBuilderParameters) params.iterator().next();
    112        setUpBasicParameters(decl.getConfigurationBuilder()
    113                .getConfigurationUnderConstruction(), basicParams);
    114        // now properties set explicitly can be overridden
    115        super.initializeParameterObjects(decl, params);
    116    }
    117
    118    /**
    119     * Populates the specified parameters object with properties from the given
    120     * configuration. This method is used to set default values for basic
    121     * properties based on the result configuration of the parent builder.
    122     *
    123     * @param config the configuration whose properties are to be copied
    124     * @param params the target parameters object
    125     */
    126    private static void setUpBasicParameters(final CombinedConfiguration config,
    127            final BasicBuilderParameters params)
    128    {
    129        params.setListDelimiterHandler(config.getListDelimiterHandler())
    130                .setLogger(config.getLogger())
    131                .setThrowExceptionOnMissing(config.isThrowExceptionOnMissing())
    132                .setConfigurationDecoder(config.getConfigurationDecoder());
    133    }
    134}